This invention relates to a multiple bolt-type fastener and to the method of fabrication of such a fastener.
Bolt-type fasteners having a threaded shank and an integral head are widely used for interconnection and fastening of elements to each other. A twist or turning force is, of course, applied to the head for insertion and removal of the fastener. Fastening bolts are manufactured in many different lengths, but generally only the shorter length bolts are immediately available. Although certain suppliers may stock various long sizes of particular bolts, longer bolts are not generally and conveniently available on demand, particularly for the small user such as the retail purchaser.
The prior art includes suggestions for forming a bolt-type fastener from an elongated threaded rod, which is generally available in lengths substantially greater than three inches. The rod is cut to an appropriate size and a head permanently fixed to the one end. For example, U.S. Pat. No. 2,180,139 which issued in 1957 and U.S. Pat. No. 3,468,211 which issued Sept. 23, 1969 both disclose an axially inserted locking element introduced from the outer end of the rod into the nut to lock it to a stud or rod member and thereby form a threaded bolt-type fastener. U.S. Pat. No. 3,468,211 also notes the use of such structure may be advantageous where the shank or head must be of a special material. Thus, if a hardened, high strength shank is desired, the separate shank and head may provide an efficient and easier mode of manufacture. The prior art systems, however, require use of a nut with access to the end of the interconnected rod and nut, can not be easily incorporated into a socket drive head, and produce a connection of limited strength. Further, the assembly and fabrication of the rod and nut into the integrated fastener requires rather skilled technique to insure a firm reliable connection.